Splined assembly

ABSTRACT

A splined assembly 10 is disclosed and includes a generally annular outer spline member 12 into which a second generally annular inner spline member 14 is rotatably placed. Member 12 includes a plurality of splines 22, 24, each having a snap ring reception slot 30 formed therein. In a first embodiment, housing member 12 also includes a band 34 which substantially surrounds the housing member 12 and overlays slots 30. In a second embodiment, housing 12 includes a plurality of elliptically protruding portions 40, each of which is positioned between pairs of adjacent splines 22, 24. Both band 34 and portions 40 are effective to prevent structural deformation caused by the received snap ring.

FIELD OF THE INVENTION

This invention relates to a splined assembly and, more particularly, toan assembly having a first annular splined housing member rotatablycontained within a second annular splined housing member.

DESCRIPTION OF THE PRIOR ART

Splined assemblies, usually comprising a first annular splined housingmember rotatably contained within a second annular splined housingmember, are employed in automotive transmissions, brake assemblies, andin many other apparatuses.

More particularly, each of the splined members usually has a generallyannular body having splines circumferentially formed around the outerbody surface. Each adjacent pair of splines provides an included platereception groove which is adapted to receive clutch plates, which aremovably and stackably disposed between the two members. Moreover, thesnap or retainer ring is usually movably seated within retentiongrooves, formed within the uppermost or root portion of each spline ofthe second member. As is known in the art, the snap ring is adapted tobe engaged by the movably stacked plates, thereby ensuring that theplates remain disposed between the two members and do not become axiallyseparated from the assembly.

As is further known, the plates normally reside at the bottom portion ofthe assembly, between the outer surface of the contained first memberand the inner surface of the second member. In this position, the platesare in disengaging relation to the plate reception grooves, therebyallowing the two members to independently rotate. Thereafter, as isknown in the art, the plates are axially moved within the assembly, bymeans of a piston and made to forcibly engage the snap ring, therebythrusting the snap ring against the root portion of each spline.

In this second thrusted position, the teeth of each of the stackedplates are seated or contained within one of the plate reception groovesformed between adjacent splines of a certain one of the members, therebycooperatively interlocking the two members and forcing the members torotate in unison. One example of such a known splined member is thatdescribed and claimed within U.S. Pat. No. 4,014,619 (the '619 patent),filed on Sept. 29, 1975; issued on Mar. 29, 1977; assigned toApplicant's Assignee; and fully incorporated herein by reference.

These snap ring retention grooves are usually formed, as explained inU.S. Pat. No. 4,813,522, ("the '522 patent"), issued on Mar. 21, 1989 toFujioka, et al and assigned to Nissan Motor Company Limited, by"pressing out" and rupturing a predefined portion of each spline. Whilethese "pressed out" and partially ruptured portions have allowed for theproper seating of the snap ring, they are known to be structurally weakand tend to deform due to the relative large force imparted on them bythe thrusted snap ring. Therefore, and as explained in the '522 patent,each annular member has been usually formed form a relatively thicksteel plate, in order to ensure that the "pressed out" portions possesssufficient structural strength to resist deformation. Disadvantagesassociated with the use of such a thick steel plate, as furtherdescribed in the '522 patent, include the need for a "special machine"with which to "press out" and rupture portions of the relatively thicksteel and a relatively long member "production time". One approach toincrease structural strength while reducing production cost is found inthe '619 patent and involves the formation of slots in the root sectionof each spline. This approach has been found to be very effective andthe embodiments of this invention as will be explained, may be used incombination with the teachings of the '619 patent to further increasestructural strength.

Attempts to obviate the use of these thick plates while still producinga member having an acceptable structural strength include, as disclosedin the '522 patent, rupturing only one wall of each spline, whiledeforming or "bulging" the remaining wall portion. In this manner, thedeformed portion supposedly "functions as a rib to increase thestrength" of each spline while the snap ring seats within a relativelysmall groove formed by the single ruptured side wall.

This approach not only fails to adequately strengthen the member butalso fails to consistently and adequately allow the snap ring to remainseated within the formed groove, since the snap ring is seated withinonly a relatively small portion of each spline. Accordingly, the ringhas a tendency to dislodge when axially engaged by the snap ring,thereby causing assembly failure.

Another approach to increase spline strength is also described in the'522 patent and requires the use of "extruded channels" to "stop thesnap ring" outside of the splined member. This approach again fails tostrengthen the member. Moreover, these channels require complexproduction apparatuses and do not adequately ensure that the snap ringremains continuously seated within the retention grooves. For thesereasons, this approach has also failed to address the difficultiesassociated with the prior art.

A further approach to alleviate these prior difficulties is described inU.S. Pat. No. 3,922,932, ("the '932 patent"), issued on Dec. 2, 1975 toMaurice, et al and assigned to Regie Nationale des Usines Renault. Asdescribed, abutments are formed adjacent to the usual snap ring apertureand are adapted to prevent the plates from axially separating from theassembly, thereby obviating the need for resilient snap rings andsupposedly simplifying overall assembly production.

While these abutments axially immobilize the various clutch disks, theyhave been prone to structural deformity, have not adequately orconsistently prevented the plates from separating from the assembly, andhave failed to structurally strengthen the member.

There is therefore, a need to provide a splined assembly adapted toaxially immobilize the several movably disposed clutch plates whilemaintaining structural integrity irregardless of the axial thrust forceimparted to it by the contained plates and the snap ring.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a splined assembly adaptedto movably contain several clutch plates.

It is another object of this invention to provide a splined assemblyincluding a splined member having snap ring retaining slots formed ineach of the splines, the slots being adapted to cooperatively receive asnap ring which is effective to prevent the several contained clutchplates from axially separating from the assembly.

It is a further object of this invention to provide a splined housingassembly including at least two splined housing members, the assemblyhaving a band which is circumferentially positioned and coupled to theouter surface of one of the splined housing members and which is adaptedto overlay each of the snap ring retaining slots formed within that onesplined housing member.

It is yet a further object of this invention to provide a splinedhousing assembly including an outer splined housing member havinggenerally elliptically-shaped protruding or outwardly projectingportions which are each positioned between pairs of splines and whichcooperatively allow the member to resist spline deformation.

According to a first aspect of this invention, a housing member isprovided and comprises an annular splined body having lanced slotsformed in the root section of each of the splines, the lanced slotsbeing adapted to cooperatively and movably receive a snap ring.Moreover, the body further includes substantially identical protrudingportions formed between each of the splines, the protruding portionsbeing adapted to cooperatively allow the member to resist deformation.

According to a second aspect of the present invention a method isprovided for preventing the deformation of snap ring reception splinesformed in a housing. The method includes the steps of forming a band;and coupling the band to the housing such that the coupled bandsubstantially surrounds the housing and overlays the root section ofeach of the formed splines.

Further objects, features and advantages of the invention will becomeapparatus from the consideration of the following description andclaims, when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Various advantages of the present invention will become apparent tothose skilled in the art by reading the following specification byreference of the following drawings in which:

FIG. 1 is a fragmented plan view of the splined assembly made inaccordance with the teachings of a first embodiment of this invention;

FIG. 2 is a cross-sectional view of the splined assembly shown in FIG. 1and taken along view line 2--2;

FIG. 3 is a cross-sectional view of the splined assembly shown in FIG. 1and taken along the view line 3--3;

FIG. 4 is a fragmented perspective view of the splined assembly shown inFIG. 3, taken along view line 4--4, and illustrating the teachings of asecond embodiment of this invention;

FIG. 5 is an elevational view of the portion of the splined assemblyshown in FIG. 4; and

FIG. 6 is a fragmented perspective view of the splined assembly shown inFIG. 1 and taken along the view line 6--6.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1 and 2, there is shown a splined assembly 10,made in accordance with the teachings of a first embodiment of thisinvention. As shown, assembly 10 includes a first outer and generallyannular splined housing member 12 which is adapted to movably androtatably contain a second generally annular splined housing member 14.

As shown best in FIGS. 1, 2, 3, and 6, several clutch plates, such asplates 16 and 18, are normally disposed between housings 12 and 14 and,as is known in the art, are made to initially reside upon the bottomportion 19 of housing 12, between the inner surface of member 12 and theouter surface of member 14. Thereafter, as is known in the art, a pistonor other means (not shown) causes the plates 16, 18 to be movably seatedwithin the included grooves 20, formed between adjacent splines 22, 24on one of the housings 12, 14. Moreover, plates 16 and 18 are normallyseparated by a friction plate 26 which further immobilizes the seatedplates 16, 18 and further ensures that the plates 16, 18 remain seatedwithin grooves 20, thereby causing housings 12, 14 to selectively andinterlockingly rotate in unison.

As further shown in FIGS. 1 and 6, assembly 10 also includes a snap ring28 (shown in phantom in FIG. 1) which is adapted to be movably receiveby each of the lanced snap ring retaining slots 30 which aretransversely formed across and through the entire root section of eachof the splines 22, 24, of the outer housing member 12. As shown, eachslot 30 is formed by lancing or rupturing both of the side walls 31, 33of each spline root section.

Ring 28 is adapted, as is known by those of ordinary skill in the art,to become engaged by plates 16, 18, and 26 as they are movably seatedwithin grooves 20 and is adapted to prevent the plates 16, 18, 26 fromaxially separating or exiting from the top portion of assembly 10.Moreover, as is known, the engaging plates 16, 18, 26 force ring 28against each of the spline portions 32, lying above one of the slots 30.This force, as previously explained, is sometimes large enough to deformor bend spline portions 32, thereby causing ring 28 to move away fromthe corresponding plate retention position and allowing axial separationof the plates 16, 18, 26 from the assembly. In order to substantiallyprevent this deformation, it has been determined that assembly 10 shouldbe modified in accordance one of the following two alternativeembodiments of this invention.

Referring now to FIGS. 1 and 2 there is shown a band 34, which in afirst embodiment of this invention, is placed around the outercircumference of housing member 12, such that the band substantiallysurrounds and is welded or attached to housing 12 while overlaying eachof the slots 30 of splines 22, 24.

This welding most preferably comprises laser welding in order tomaintain structural strength of the welded member 12. Such laser weldingis known to those skilled in the art.

In this manner, band 34 adds columnar strength to each of the splines22, 24 (and to member 12 in the vicinity of splines 22, 24), therebyopposing or preventing the deformation of portions 32 caused by theaxial thrust of the snap ring 28. It should be realized that band 34 maybe of any desired thickness and width, the only requirement being thatis overlay slots 30. Moreover, it should also be realized that band 34may be made of steel or any other desired material that would strengthenassembly 10 in the previously described manner.

In a second embodiment of this invention, and as best shown in FIGS. 4and 5, generally elliptically-shaped and substantially identicalprotruding or outwardly projecting portions 40 are formed or "punchedout" from the housing member 12 and project outwardly from the surfaceof housing 12. More specifically, these portions 40 are positionedbetween each pair of adjacent splines 22, 24 and between each pair ofadjacent slots 30, and further cooperatively oppose or prevent thedeformation of portion 32 by adding columnar strength to each of thesplines 22, 24 (and to member 12 in the vicinity of splines 22, 24). Itshould be realized that portions 40 may be of any desired shape and beof any desired dimension, the only requirement being that the portionsprovide the necessary strength to assembly 10.

It is to be understood that the invention is not limited to the exactconstruction illustrated and described above, or that various changesand modifications may be made without departing from the spirit andscope of the invention, as defined in the following claims. Moreover, itshould also be realized that the use of the aforedescribed embodimentsallow for the use of a relatively thin steel plate to form members 12,14 and that this invention is applicable to assemblies having more thantwo rotating housing members.

I claim:
 1. A housing assembly comprising:a snap ring; an annular bodyhaving a plurality of splines, a lanced slot formed in a root section ofeach of said plurality of splines, each of said slots receiving saidsnap ring, said body further having a groove portion formed between eachpair of adjacent splines, and an outwardly projecting portion formed onan outer peripheral surface of each groove portion, wherein saidprojecting portions structurally strengthen said housing assembly in avicinity of each of said lanced slots.
 2. A housing assemblycomprising:a snap ring; an annular body having a plurality of splines, alanced slot formed in a root section of each of said plurality ofsplines, each of said slots receiving said snap ring, said annular bodyfurther having a groove portion formed between each pair of adjacentsplines; and a band coupled to said annular body and overlying each ofsaid groove portions and each of said lanced slots, wherein said bandstructurally strengthens said housing assembly in a vicinity of each ofsaid lanced slots.